A final burst of radio signals marked the end of NASA's contact with the Cassini spacecraft, which plunged into Saturn's atmosphere and disintegrated after a 20-year mission to study the ringed planet.

During that time it has sent back some incredible images to Nasa and the European Space Agency, including detailed images of Saturn, its rings and its moons.

The safe disposal of Cassini was viewed as the best way of avoiding the remote possibility of contaminating the pristine moons with Earth bugs. Cassini performed its job well till its end as it sampled the atmosphere of Saturn on Friday morning while making its final plunge. That's because of the distance between Saturn and Earth, which spans almost a billion miles.

After 13 years of examining the wonders of Saturn and its surroundings, Cassini's journey in space has ended in fire after a last flood of data. NASA predicted it would receive the final signal at 7:55AM ET, and wound up getting it about half a minute later than expected.

The spacecraft's dive to the planet is the final step of the mission, which was to take pictures and collect key information about its environment.

The finale of the mission, which NASA will broadcast and comment live on September 15, were prepared in advance: from April this year, the probe for 22 weeks did "the dip" between the rings of the planet, gradually approaching her.

The facility is one of only three in the world capable of communicating with Cassini, and on Friday night, Saturn will be visible in the Australian sky.

Scientists feared a collision with Titan or Enceladus, two of Saturn's moons that in the past 10 years have shown a potential to host simple life.

NASA is publishing the final images as Cassini descends on a special website.

Every week, Cassini has been diving through the approximately 2,000-kilometre-wide gap between Saturn and its rings.

Huygens landed successfully on one of Saturn's moons, Titan in 2005. Project officials invited ground telescopes to look for Cassini's last-gasp flash, but weren't hopeful it would be spotted from a billion miles away. Cassini remained in orbit around Saturn, the only spacecraft to ever circle the planet.